The influence of alkylaminopyridine additives on the performance of a bis(tetrabutylammonium)cis-bis(thiocyanato)bis(2,2'-bipyridine-4-carboxylic acid, 4'-carboxylate)ruthenium(II) dye-sensitized TiO2 solar cell with an I-/I-3(-) redox electrolyte in acetonitrile was studied. 3 The current-voltage characteristics were measured for more than 20 different alkylaminopyridines under AM 1.5 (100 mW/cm(2)). The alkylaminopyridine additives tested had varying effects on the performance of the cell. All the additives decreased the short circuit photocurrent density (J(sc)), but increased the open-circuit photovoltage (V-oc) of the solar cell. Molecular orbital calculations imply that the dipole moment of the alkylaminopyridine molecules influences the J(sc) of the cell and that the size, solvent accessible surface area, and ionization energy all affect the V-oc of the cell. The highest V-oc of 0.88 V was observed in an electrolyte containing 4-pyrrolidinopyridine, which is comparable to the maximum V-oc of 0.9 V for a cell consisting of TiO2 electrode and I-/I-3(-) redox system. (C) 2003 Elsevier B.V. All rights reserved.